Vehicles driven over adverse riding surfaces, such as snow, ice, or mud employ traction devices to improve operating performances. The traction devices include a substantially cylindrical stud having either a conical or wedge shaped bit. The conical bit defines a circular cone having a circular cross section transverse to the direction of penetration into the riding surface. The tip of the cone penetrates the riding surface to improve traction. The wedge shaped bit defines a planar wedge which penetrates the riding surface to improve traction.
The bit is either affixed to the stud or integrally formed with the stud. The stud includes a threaded portion and a peripheral flange defining wrench flats.
A washer and T-nut are used to affix the stud to the track. The washers have either a circular or a square periphery. The washer includes a concentric aperture sized to receive the cylindrical portion of the stud. The portion of the washer adjacent the aperture is convex forming a domed portion defined by a spherical radius of approximately 2 to 3 inches. The T-nut is a planar circular piece having a threaded sleeve projecting from one side. Three prongs extend from the same side. The prongs are equally spaced approximately 120.degree. apart about the periphery. The stud is passed through the washer so that the wrench fiats contact the convex side of the washer. The threaded portion of the stud is then disposed through an aperture in the track so that the threaded portion extends towards the inside of the track. The T-nut engages the stud and draws the wrench flats against the washer, thereby drawing the washer against the track, and the prongs of the T-nut into the back side of the track.
Due to the tremendous forces exerted upon the traction device, it is desirable to have the contact area between the washer, T-nut, and the track as large as possible. The large surface area minimizes damage to the track as forces are exerted on the traction device. However, the large contact surface area has specific drawbacks. The edges of the large surface area introduce excessive wear as the track passes over the idler wheels. The flexing of the track over the idler wheels causes the edges of the washer and T-nut gouge the track. Therefore, there are benefits to reducing the contact area. In addition, as the T-nut rotates past the idler wheels, the prongs temporarily disengage the track, and then re-engage as the T-nut passes beyond the idler wheel. The repeated withdrawal and insertion of the prongs into the track locally weakens the track.
In an attempt to provide a balance between increased contact area and track wear, transverse cleats have been used across the width of the track. The cleats extend perpendicular to the direction of rotation. A plurality of traction devices may be cooperatively engaged with the track along the width of the track. However, the cleats require a plurality of traction devices, and add significant weight to the track which weight also introduces extra wear.
Traditionally, the tracks have included a plurality of longitudinal reinforcing fibers extending along the direction of track, or belt travel. The reinforcing fibers provide additional strength to the track. However, the fibers increase the resistance of the track to rotation, thereby increasing horsepower requirements.
New track constructions are formed without the longitudinal reinforcing fibers. The lack of fibers reduces rolling resistance and horsepower requirements. However, without the longitudinal fibers, the aperture in the track through which the stud, or shaft of the traction device passes tends to substantially deform. The deformation may be sufficient to permit one of the inner plate (T-nut) or outer plate (washer, backing plate) to pass through the deformed aperture, thereby causing complete failure of the traction assembly. Therefore, a need exists for precluding catastrophic deformation of the aperture.